Basically, such block machines, core puller devices for block machines, but also methods for the preparation of shaped stones are known. Here, the core puller devices are for the generation of at least one recess in at least one shaped stone to be prepared in a block machine. Here, a particularly common field of application is the preparation of concrete blocks that are used e.g. as paving blocks, masonry blocks, or building blocks. However, for the object of the invention all of further shaped stones of any shape and any material are also relevant for which a recess has to be generated and that undergo a packing operation during preparation. Here, the recesses can take over several functions, such as for example weight saving, insulation, or a better handling of the shaped stones in the further manufacturing process.
To generate the recess such a core puller device has at least one core puller that is often laterally inserted into the stone mould of the block machine and is again retracted after a packing process. Generally, the core puller thus is formed as an elongated metal rod. However, the core puller can also have a different shape or nature depending on what recess(es) is/are to be achieved in the shaped stone or shaped stones and depending on how the stone mould or block machine, respectively is configured.
By the use of several core pullers several shaped stones can be provided with recesses. Also, it is possible to generate several recesses in one shaped stone or in several shaped stones at the same time. In case that several shaped stones are to be prepared at the same time the stone mould has several moulding cavities that are configured such that they are penetrated by one core puller behind the other and/or also by further core pullers lying next to each other.
In order to insert the core pullers into the stone mould of the block machine these are often attached to a sliding facility. This is suitably attached to a rack and moves relative to the stone mould. It is also conceivable that the sliding facility is directly arranged on the block machine. However, also free-standing solutions are possible in which the core puller devices have their own rack and virtually can be placed next to the block machines.
Here, the core pullers typically are firmly and generally permanently connected to the sliding facility in order to be able to quickly, safely, and directly insert them into the stone mould and remove them again after the packing operation.
During the packing operation the stone mould is generally set vibrating in order to achieve a uniform packing of the material in the stone mould. Here, it has been shown that especially when using a core puller device the packing not always is to the full satisfaction. This is because there is no quite uniform packing in the material in the stone mould.
The reason for this phenomenon has already been recognized in the past to be the core puller device and provided it with dampers. However, tests of the applicant have shown that the results are still unsatisfactory, since in individual cases undesirably packed shaped stones are made.